Conventionally, administration instruments for medical use have frequently been used in administering drug solutions such as insulin or hormone preparations. Generally, such an administration instrument for medical use includes a needle, a syringe body, and an injection button, which are almost aligned, thereby pushing an injection out of a drug solution cartridge that is housed in the syringe body in a direction that is parallel to the needle by the injection button. FIGS. 24 and 25 show two typical devices of the prior art
In FIG. 24, reference numeral 201 denotes a body of an administration instrument for medical use (hereinafter, also referred to as a syringe body), numeral 202 denotes an injection that is sucked in the body 201 of the administration instrument for medical use, numeral 203 denotes an injection button, numeral 204 denotes a needle, and numeral 205 denotes a plunger of a part that is connected to the injection button 203 and directly pushes the injection 202 out of the syringe.
The syringe body 201 contains the injection 202. When the injection is to be administered, the needle 204 is inserted into the skin, and the injection button 203 is pressed, thereby forcing the injection 202 out of the body 201 of the administration instrument for medical use. The amount of the injection 202 administered is decided by adjusting the amount of press onto the injection button 203 is pressed.
That is, an administrator (patient) pushes the injection button 203 to move the internal plunger 205, thereby forcing the injection 202 out of the needle 204. The amount sliding of the plunger 205 that slides will decide the amount of the injection that is administered. The administrator (patient) decides the amount of the injection 202 to be administered, inserts the needle 204 into a desired position on the skin, and presses the injection button 203, thereby completing the injection. When the needle 204 is inserted into the skin, the administrator (patient) must decide the amount of the insertion of the needle into the skin based on his/her past experiences or the like.
Most of the administration instruments for medical use that are used for self-administration are mechanical or pen types, as shown in FIG. 24. Since the injection button is pushed in the same direction as the initial insertion of the needle into the skin in such instruments, the state of the administration becomes unstable. On the other hand, as shown in FIG. 25, to solve the above-mentioned problem, recently contrived is an administration instrument for medical use including a portion which touches the skin at the administration near the needle, thereby deciding the positions of the needle and the skin to provide the stability of administration.
In FIG. 25, numeral 301 denotes a body of the administration instrument for medical use, numeral 303 denotes an injection button, numeral 304 denotes a needle, numeral 306 denotes a skin touch portion that is touched on the skin in administrating an injection using this conventional administration instrument for medical use, numeral 307 denotes a drug solution cartridge, and numeral 302 denotes an injection in the drug solution cartridge 307.
At the administration, the needle 304 is inserted into the skin with the skin touch portion 306 touching the skin, and the injection button 303 is pressed to force the injection 302 out of the drug solution cartridge 307. The amount of the administration is decided by adjusting the amount of pressing onto the injection button 303 is pressed.
In most cases of the conventional administration instrument for medical use, the needle is attached to the instrument body immediately before the actual administration of the injection, and a decided amount of a drug solution is administered to a human body after performing preliminary pressing (hereinafter, also referred to as air removal) to prevent air from being injected with the injection.
In the conventional administration instrument for medical use, the external view of which is shown in FIG. 24, when administering the drug solution, it is possible to push the injection button or the administration button also in a state where the needle is not attached to the administration instrument body. Accordingly, the injection button or the administration button may be inadvertently pushed, thereby causing a problem.
Further, in the case of the conventional administration instrument for medical use, a doctor conducts a diagnosis to give instructions as to the amount of an injection to be administered and the interval of the administration, and the administrator performs self-administration of the drug solution in accordance with these instructions, while management of the amount of the injection administered and the interval of the administration is left to the administrator himself/herself. In addition, the doctor regularly conducts the diagnosis, and newly decides the amount of the injection to be administered and the interval of the administration on the basis of the result of the diagnosis, the amount of the injection that was administered, and the interval of the administration, thereby giving new instructions.
Conventionally, the mechanical administration instruments for medical use, as shown in FIGS. 24 and 25, have been often used for self-administration, while some instruments that are provided with electronic devices have been recently contrived.
A typical structure of this instrument is shown in FIGS. 26 and 27. Further, FIG. 28 shows a block diagram with a microprocessor shown in the center. FIG. 26 is a front view of the instrument, and FIG. 27 is a top view thereof partially illustrated in cross section.
In FIG. 26, numeral 403 denotes a syringe body, numeral 401 denotes a needle, numeral 404 denotes a display section, numeral 405 denotes a dial for setting the amount of an injection to be administered, and numeral 406 denotes an injection button.
In FIG. 27, a cartridge 407 containing an injection 426 is placed in the syringe body 403. The administrator pulls out the injection button 406 before the injection. When the injection button 406 is pulled out, a sleeve 418 and a nut 412 also slide together with the injection button 406 in the same direction as the injection button 406.
By the sliding of the sleeve 418, a spline portion 416 of the sleeve 418 is coupled to a spline portion 417 of the administration amount setting dial 405. The coupled portion of the sleeve 418 and the plunger 408 is not fixed in the sliding direction but fixed in the rotational direction. The coupled portion of the sleeve 418 and the nut 412 is not fixed in the rotational direction but fixed in the sliding direction.
As a result, when the administrator rotates the administration amount setting dial 405, the sleeve 418 is rotated, and the plunger 408 is accordingly rotated, whereby the plunger 408 is slid by a thread that is provided on the inner circumference of the nut 412 and a thread that is provided on the outer circumference of the plunger 408. The amount of the injection to be administered is decided depending on the amount of the sliding of the plunger 408. When the injection button 406 is not pulled out, the sleeve 418 and the administration amount setting dial 405 are not coupled, whereby even when the administration amount setting dial 405 is rotated, the plunger 408 will not move.
The administrator rotates the administration amount setting dial 405 to decide the amount of the injection to be administered, insets the needle 401 in a position where the administration is to be performed, and then depresses the injection button 406, thereby completing the injection. When the injection has been completed, the injection button 406, the sleeve 418, and the nut 412 are slid in a direction in which they are depressed. In order to detect that the injection button 406, the sleeve 418, and the nut 412 have been slid, a projection 420 is provided on the sleeve 418, and a switch 413 that is turned on or off by the projection 420 is fixed on the body 403.
The switch 413 is turned on when the injection button 406 is pulled out, while the switch is turned off when the injection button 406 is depressed. The completion of the injection is detected by observing the state of the switch 413. As a means for judging the completion of the injection according to the state of the switch 413, a microprocessor 425, as shown in FIG. 28, or the like, is employed, and the completion is judged by judging a conduction state of the switch 413.
Here, numeral 417 denotes a spline portion of the setting dial 405, numeral 419a and 419b denote optical sensors, numeral 414 denotes a liquid crystal display, numeral 415 denotes a board, numeral 421 denotes a rotational plate, and numeral 421a denotes a rotational plate slit. In FIG. 28, numeral 422 denotes a memory of the microprocessor 425, numeral 423 denotes a calendar, numeral 424 denotes a clock, and numeral 404 denotes a display interface with the liquid crystal display 414.
FIG. 29 is an enlarged view illustrating a part for detecting completion of the injection. When setting the amount of the injection to be administered is to be set, the administration amount setting dial 405 and the sleeve 418 are rotated. The amount of the injection administered is decided depending on the amount of motion of the plunger 408, which is caused by rotation of the administration amount setting dial 405. Therefore, a method is employed in which the amount of the injection administered is detected by detecting the rotation of the administration amount setting dial 405 and the sleeve 418, and the amount of the rotation. Here, numeral 416 denotes a sleeve spline portion, and numeral 417 denotes a setting dial spline portion.
For example, as shown in FIG. 30, the rotational plate 421 that rotates together with the administration amount setting dial 405 is provided, and the slits 421a are formed on the rotational plate 421 as shown in FIG. 31, and two optical sensors 419a and 419b are provided at positions where light crosses the slits 421a. When the administration amount setting dial 405 is rotated, the rotational plate 421 is also rotated, and the slits 421a that are provided on the rotational plate 421 pass through or interrupt the light of the optical sensors 419a and 419b. Since the optical sensors 419a and 419b output an ON signal or an OFF signal depending on the amount of light, it is possible to detect the rotation and the amount of the rotation in accordance with the ON or OFF signal outputted from the optical sensors 419a and 419b. 
Here, the reason why two optical sensors 419a and 419b are employed is because the amount of the injection administered is increased or decreased according to the direction of the rotation of the administration amount setting dial 405. The rotation direction is judged on the basis of a phase difference of ON or OFF of the outputs from the two optical sensors 419a and 419b, and the amount of the injection to be administered is detected by counting the number of ON or OFF of the outputs from the optical sensors 419a and 419b. As described above, the microprocessor 425 or the like is employed as shown in FIG. 32 as the means of judging the rotation direction based on the phase difference of the outputs from the optical sensors 419a and 419b, and detecting the amount of the injection to be administered by counting the number of ON or OFF of the outputs from the optical sensors 419a and 419b. 
Further, by providing the microprocessor 425 and the memory 422, recording or display of the time and date of the completion of the injection is also performed. In addition, using, for example, optical sensors 419a and 419b, sensors that utilize a switch or the like are contrived.
However, in the conventional administration instrument as shown in FIG. 24, since the needle 204 is inserted into the skin at the administration, and the injection 202 is administered with pressing the injection button 203 in the same direction as that of the insertion of the needle 204 into the skin, the needle 204 would be inserted deeper into the skin from the state where the needle is initially inserted into the skin, thereby increasing the pain of the patient at the administration.
Further, also at the administration in a case where the administration instrument for medical use is provided with the skin touch portion 306 as shown in FIG. 25, the needle 304 is inserted into the skin with the skin touch portion 306 touched on the skin, and then the injection 302 is administered by pressing the injection button 303 in the same direction as the insertion of the needle 304 into the skin. Therefore, also in this case, the above-mentioned problem that the needle 304 would be inserted into the skin deeper from the state where the needle is initially inserted into the skin occurs because, even when the skin touch portion 306 is provided, the actual skin has the elasticity and thus the needle 304 would be inserted into the skin deeper by a force of the actual pressing of the injection button 303.
To avoid this problem, it is necessary to fix the arm by which the injection button 303 is pressed in midair or by some method with care during the administration. However, it is quite difficult when the administration of the drug solution is performed by the patient himself/herself.
When the needle is inserted into the skin deeper during the administration, the pain of the patient would be increased, which is not only distressing both physically and mentally but in some cases may exert many influences upon the body of the administrator (patient), resulting in a hazardous condition to his/her life.
Further, in the conventional administration instrument for medical use as shown in FIG. 24 or 25, since the needle is not always uniform and the length of the needle is different depending on the type, the amount of the needle that is inserted into the skin varies and, in some cases, the failure of the injection or the burden of pain becomes large, and serious influences may be exerted upon the body of the administrator (patient), resulting in a hazardous condition to the life.
Further, in the conventional administration instrument for medical use as shown in FIG. 24, it is possible to press the injection button or the administration button even when the administrator forgets about attaching the needle to the administration instrument body. Therefore, following problems arise.
One of the problems is as follows. When the injection button or the administration button is pressed without the needle attached, the drug solution may be leaked out of the end portion of the syringe opposite to the injection button or the administration button or the drug solution may flow backward and leak toward the injection button or the administration button, like a leaking drug solution 221a or a backward flowing drug solution 221b in FIG. 33, or, as shown in FIG. 34, the glass tube itself containing the drug solution obtains cracks 227 or is ruptured due to a force that is generated by the pressing of the injection button or the administration button, and broken, whereby the drug solution leaks outside.
Further, also in cases where two types of drug solutions are mixed or a drug and a drug solution are dissolved, such as growth hormone preparations, it is necessary to perform the mixture after the needle is attached to the instrument. Accordingly, when the administrator forgets about attaching the needle, it is impossible to achieve the mixture, and further the back-flow or leakage of the drug solution, or the cracking or rupture of the glass tube of the drug solution cartridge adversely occurs as described above. Many of the above-mentioned problems frequently occur, particularly when the patient performs the administration by himself/herself.
Further, in the case of the conventional administration instruments for medical use as shown in FIGS. 24 to 27, the risk of accidents may be low when the doctor or the nurse administers the drug solution, but when the patient by himself/herself performs the administration, an operation of removing air from the syringe which is always performed before the administration may be forgotten if he/she does not always keep it in mind. When the air removal is forgotten, the human bodies of some people may be affected seriously, possibly resulting in a hazardous condition to life.
Further, in the conventional administration instrument for medical use as shown in FIG. 26 or 27, the amount of the injection that has been administered can be displayed on the electronic display unit, but the amount of the injection, the date, and the time at the air removal operation that is always performed before the administration are also recorded in the memory 422, whereby the available space of the memory 422 is uselessly reduced. In addition, since the amount of the injection at the air removal operation is also displayed together with the essential injection amount, when the doctor checks the result of the diagnosis and the past administration history of the administrator (patient) to decide the future remedy, there is a risk that the doctor makes a wrong diagnosis. If the doctor makes such a wrong diagnosis, the body of the administration (patient) may be seriously affected, and a hazardous condition to the life may be produced.